In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date:    (i) part of common general knowledge; or    (ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.
With the uptake of broadband connections has come a corresponding increase in the volume of audiovisual material viewed over point-to-point communication networks, such as the Internet. This increase in viewer numbers is in turn motivating content providers to release more content onto the Internet for viewing. Moreover, in view of developing applications such as IPTV and wireless connection technologies and devices, it is likely that point-to-point networks will grow in stature as communications platforms for audiovisual content, even to the point of rivaling traditional broadcast networks.
Software and hardware architectures for audiovisual streaming have largely developed around the delivery of pre-recorded content—a process known as ‘on-demand’ streaming—with less consideration given to the task of streaming live content.
An example of a live streaming system is described in A Transport Layer for Live Streaming in a Content Delivery Network Proceedings of the IEEE, Volume: 92, Issue: 9 page(s): 1408-1419 in which a complex Content Delivery Network (CDN) is deployed to transport live streams to end users.
As known to those skilled in the art, CDNs operate by replicating contention network nodes that are strategically distributed throughout the globe to be closer to end users in terms of network hops. The nodes—each of which may comprise a number of servers—tend to be privately owned by enterprises that offer content delivery services to large web sites, and cooperate with each other to satisfy requests for content by end users, transparently moving content behind the scenes to optimize the delivery process.
Optimization can take the form of reducing bandwidth costs, improving end-user performance, or both.
When optimizing for end-user performance, locations that can serve content quickly to the user may be selected. This selection may be realised by choosing locations that are the fewest number of hops or fewest number of network seconds away from the requester, so as to optimize delivery across local networks. When optimizing for cost, locations that are less expensive to serve from may be selected.
Broadly speaking, the Live streaming CDN includes: Entry Point Machines that act as origin proxies for the encoded multimedia data comprising the live stream; Set Reflectors to which the stream data is fanned from the Entry Points; and Streaming Servers, which are themselves grouped in regions and linked by a private multicast network. Streams are supplied to the individual users from the Streaming Servers via a unicast protocol.
Every effort is made to maintain a continuous flow of stream data from the Entry Points to the Streaming Servers, through various packet recovery techniques, including inserting parity packets within a stream or across a combination of streams, Reed-Solomon codes and retransmits, as well as adaptive multipath transmission across various Set Reflectors.
The present invention aims to provide an alternative approach to the task of streaming content, and in particular live content over communication networks.